1. Field of Invention
The present invention relates to a lens, and more particularly to a projection lens which is capable of effectively converging, by virtue of a predetermined pattern of diffraction, diverging light beams emitted from a single light source, such as a LED, to form a high intensity, coherent and high quality light effect having an accurate projection angle.
2. Description of Related Arts
LED (Light Emitting Diode) has been widely utilized as an efficient and comparatively economical light source for providing illumination in different surrounding circumstances. For example, a plurality of LEDs may be electrically connected to form rope light, indication light source, Christmas light string, advertisement sign board, and etc. Different combinations of LEDs of differing colors may be arranged in a particular manner such that numerous light effects can be generated for differing applications.
Over the years, engineers have been actively resolving about the limitations of conventional LEDs in an attempt to maximize the applications thereof. For example, they have developed some kinds of light holders which can convert the point of light sources into a single line source. As a result, various practical applications which are traditionally performed by expensive and non-reliable light sources, such as advertisement signs and interior/exterior decoration lighting, have been gradually replaced by LEDs applications.
In some other cases, a reflective layer is coated on the light holder so that the illumination provided by the LEDs in that particular light holder would be of improved quality and intensity. It is expected that, given the fierce competition in commercial world, the chasing for more economical yet better quality illumination devices would not stop. However, such reflection coating surface merely can provide limited effect and generally has to position behind the LED. In fact, for lighting intensity enhancement, a projection lens in front of the light source is more preferable than a reflection surface behind the light source. Moreover, during the electrolytic coating process of the reflective surface, environmental pollutants, waste water and other poisonous materials are produced too.